1. Field of the Invention
The present invention relates to a swash plate control mechanism for pivotally moving a swash plate, and to a hydraulic continuously variable transmission incorporating same. More particularly, the present invention relates to a swash plate control mechanism for pivotally moving a swash plate member, in a hydraulic swash plate plunger unit which may be a swash plate plunger pump or a swash plate plunger motor, and to a hydraulic continuously variable transmission incorporating the described control mechanism.
2. Description of the Background Art
A variety of forms and configurations of hydraulic continuously variable transmissions, including a hydraulic pump and a hydraulic motor in combination, have been known and put to practical use.
One example of a commercial hydraulic continuously variable transmission was sold by Honda and marketed under the trademark “Hondamatic” on the 2001 Honda Fourtrax Foreman Rubicon™ TRX500 ATV.
Another example of a hydraulic continuously variable transmission is disclosed in Japanese Patent Laid-open No. Hei 6-2753 and Japanese Patent Publication No. Hei 7-88884 proposed by the present applicant.
The hydraulic continuously variable transmission disclosed in these documents includes a swash plate plunger pump, a swash plate plunger motor, and a closed hydraulic circuit for connecting a discharge port and a suction port of the swash plate plunger pump to a suction port and a discharge port of the swash plate plunger motor, respectively.
In the hydraulic continuously variable transmission described in the reference, a pump swash plate member is driven by an engine, a pump cylinder and a motor cylinder are connected to each other and disposed on an output shaft. A motor swash plate member is restricted in rotation, and the motor swash plate angle can be variably regulated.
In the referenced hydraulic continuously variable transmission, the pump cylinder and the motor cylinder are connected to each other in a back-to-back relationship, and pump and motor distribution valves (distributor valves) are disposed at the connected portion, thereby forming the closed hydraulic circuit.
These pump and motor distribution valves are so structured that oil, discharged from a pump plunger reciprocated in the pump cylinder according to the rotation of the pump swash plate, is supplied into a motor cylinder chamber to push the motor plunger. Hydraulic pressure moves the motor plunger in the axial direction in sliding contact with the motor swash plate, thereby driving the motor cylinder to rotate.
In some hydraulic continuously variable transmissions and similar powertrain components, an identification mark, representing a model number, a product number and the like, may be stamped on an outside surface of the housing. Such an identification mark is located at a position such that the identification mark can be viewed from the outside, not only in the condition where the transmission is in a singular state, but also where the transmission is mounted on a vehicle.
For example, it is generally known that a cylinder block, in a V-type engine, may be provided with a machined stamping surface, to receive an identifying serial number or the like stamped thereon.
In the hydraulic continuously variable transmission disclosed in the above reference, however, the identification mark display portion is not located on the housing where the identification mark can be easily viewed from the exterior. As a result, external identification can be difficult to make, where the transmission is mounted on a vehicle.
Although the known devices have some utility for their intended purposes, there is still a need to provide an improved swash plate control mechanism, and for a hydraulic continuously variable transmission incorporating an improved swash plate control apparatus.
More particularly, there is a need for an improved swash plate servo mechanism for pivotally moving a swash plate member, in a hydraulic swash plate plunger unit, including a swash plate plunger pump and a swash plate plunger motor.